One of the primary limitations in the use of radioimmunoscintigraphic techniques to detect tumors clinically has been the difficulty in achieving high tumor to normal tissue ratios of bound radioactivity. Part of this difficulty arises from the fact that a significant proportion of monoclonal antibodies (MoAb) are inactivated during radiolabeling procedures and such MoAb, when injected intravenously, localize non-specifically in normal tissues. This proposal addresses the problem through the development of an innovative, new method for effectively separating antibodies damaged during radiolabeling procedures from those retaining their original affinity and specificity. Preliminary studies indicate that anti-idiotypic (anti-Id) MoAb recognizing the combining sites of anti-melanoma MoAb can be prepared as affinity matrices to purify the anti-melanoma MoAb after radiolabeling procedures. In this study the immunoreactivity, specificity, affinity and tumor to tissue ratios of In-111-labeled anti-melanoma MoAb will be assayed before and after immunoaffinity is effective, it may be possible to increase the sensitivity of tumor detection by radioimmunoscintigraphy. Therefore we believe a ready commercial market exists among laboratories performing clinical or experimental radioimmunoscintigraphy techniques for kits containing anti-tumor MoAb ready for radiolabeling and prepackaged anti-Id MoAb affinity columns for purification after the MoAb have been labeled.